Hydrotreating catalyst and processes for hydrotreating hydrocarbon oil with the same

ABSTRACT

The present invention relates to a hydrotreating catalyst composed of a carrier having a Brønsted acid content of at least 50 μmol/g such as a silica-alumina carrier or a silica-alumina-third component carrier, in which the silica is dispersed to high degree and a Brønsted acid content is at least 50 μmol/g, and at least one active component (A) selected from the elements of Group 8 of the Periodic Table and at least one active component (B) selected from the elements of Group 6 of the Periodic Table, supported on said carrier. The present invention also relates to a method for hydrotreating hydrocarbon oils using the same. The hydrotreating catalyst of the present invention provides excellent tolerance to the inhibiting effect of hydrogen sulfide, high desulfurization activity, and exhibits notable effects for deep desulfurization of hydrocarbon oils containing high contents of sulfur, in particular gas oil fractions containing difficult-to-remove sulfur compounds. The hydrotreating catalyst of the present invention is also very effective for hydrodenitrogenation, hydrocracking, hydrodearomatization, hydroisomerization, hydrofining and the like of hydrocarbon oils.

FIELD OF INDUSTRIAL UTILIZATION

This invention relates to a hydrotreating catalyst and a method forhydrotreatment of hydrocarbon oils using the same, more particularly tothe catalyst high in tolerance to inhibiting effects by hydrogen sulfideand nitrogen compounds and high in activity and activity-maintenance,and the method using the same for various hydrotreating purposes, e.g.,hydro-desulfurization,hydrodenitrogenation,hydrocracking,hydrodearomatization,hydroisomerization and hydrofining.

BACKGROUND OF THE PRESENT INVENTION

Various types of catalysts have been proposed for hydrotreatinghydrocarbon oils. The so-called two-element catalysts, with the Group 6elements (e.g., molybdenum and tungsten) and Group 8 elements (e.g.,cobalt and nickel) as the active metallic components carried byrefractory inorganic oxides (e.g., alumina, silica and magnesia), havebeen already commercialized. These catalysts have been further developedto have higher desulfurization and/or denitrogenation activity, bothfrom active metallic components and carriers. The applicant of thepresent invention have already studied to further improve catalystactivity by improving dispersibility of the active metallic components,to propose an extremely high-activity catalyst with high desulfurizationactivity, which is prepared by supporting cobalt and/or nickel as theGroup 8 metals on a silica-alumina carrier in the first step, andfurther supporting molybdenum and/or tungsten as the Group 6 metals onthe same carrier in the second step, to finely disperse molybdenum asthe major component on the carrier (Japanese Laid-open Patentapplication No. 225645/1985).

The carriers have been also developed, by controlling pore sizedistributions of silica-alumina carriers, to improve desulfurizationactivity of the catalysts for hydrotreating by maximizing the poreshaving a diameter of 30 Å to 100 Å.

Recently, however, reduction of sulfur content of gas oils is stronglyrequired for environmental reasons, especially for stocks of highersulfur contents, e.g., light gas oil (LGO) and vacuum gas oil (VGO). Inparticular, sulfur content of LGO is strongly required to be reduced to0.05 wt. % or lower for environmental reasons. Whether this is achievedor not largely depends on whether sulfur compounds difficult to remove,e.g., 4-methyl dibenzothiophene and 4,6-dimethyl dibenzothiophene, areefficiently desulfurized, in particular at a high hydrogen sulfidepartial pressure.

It is however known that the two-element catalysts are rapidlydeactivated, when deeply hydrotreating hydrocarbon oils of high sulfurcontent, as a result of increased hydrogen sulfide partial pressure inthe reaction atmosphere. In particular, the Ni—Mo catalyst, althoughshowing a high desulfurization activity at a low hydrogen sulfidepartial pressure, is rapidly deactivated at a high hydrogen sulfidepartial pressure, because of its insufficient tolerance to theinhibiting effects by hydrogen sulfide. On the other hand, the Co—Mocatalyst, although higher in tolerance to hydrogen sulfide to someextent, has a disadvantage of lower desulfurization activity. It istherefore necessary to develop a catalyst simultaneously showing a highdesulfurization activity and tolerance to the inhibiting effects byhydrogen sulfide, in order to deeply desulfurize hydrocarbon oils.

A variety of techniques have been proposed to solve these problems,viewed from carrier types, carrier structures, active metal componentsand method for supporting active metals on the carriers. For example,Japanese Laid-open Patent application No. 164334/1997 discloses thehydrotreating catalyst to desulfurize the difficult-to remove sulfurcompounds present in gas oil, where an inorganic oxide carrier supports5 mass % to 20 mass % (as oxide, percentage being based on the catalyst)of molybdenum in the first stage, which is dried and calcined, and thenwith 5 mass % to 15 mass % (as oxide) of molybdenum and 1 mass % to 10mass % (as oxide) of nickel in the second stage, which is dried andcalcined at 150° C. to 350° C. This catalyst, however, is aninsufficient one for the catalyst for deep desulfurization ofhydrocarbon oils, because of its low tolerance to the inhibiting effectsby hydrogen sulfide.

DISCLOSURE OF THE PRESENT INVENTION

It is an object of the present invention to provide a hydrotreatingcatalyst, developed to solve the above problems involved in theconventional catalysts, which shows high tolerance to the inhibitingeffects by hydrogen sulfide formed massively in the reaction atmosphereduring the hydrotreatment process of hydrocarbon oils of high sulfurcontent, high activity for hydrotreatment of the compounds containingdifficult-to-remove sulfur compounds, and can be used also for, e.g.,hydrodenitrogenation, hydrocracking, hydrodearomatization andhydrofining.

It is another object of the present invention to provide analumina-based hydrotreating catalyst of high silica content, in whichsilica is finely dispersed.

It is still another object of the present invention to provide ahydrotreating catalyst in which the active metals are finely dispersedby virtue of high dispersibility of silica.

It is still another object of the present invention to provide a methodof hydrodesulfurization capable of deeply desulfurizing hydrocarbon oilscontaining difficult-to-remove sulfur compounds. The inventors of thepresent invention have studied extensively to solve the problemsinvolved in the conventional catalysts, to find that the Brønsted acidsites on the hydrotreating catalyst carrier interacts with the catalystactive metals to greatly improve the catalyst tolerance to theinhibiting effects by hydrogen sulfide, with the result that thedifficult-to-remove sulfur compounds can be efficiently removed,reaching the present invention.

The present invention relates firstly to the hydrotreating catalystcomprising the carrier having a Brφnsted acid content of 50 μmol/g ormore, which supports at least one active component (A) selected from theelements of Group 8 of the Periodic Table, and at least one activecomponent (B) selected from the elements of Group 6 of the PeriodicTable.

The present invention relates secondly to the hydrotreating catalyst,comprising the carrier of silica-alumina or the carrier ofsilica-alumina a third component, which supports at least one activecomponent (A) selected from the elements of Group 8 of the PeriodicTable, and at least one active component (B) selected from the elementsof Group 6 of Periodic Table, wherein,

(i) silica content is 30 wt. % or more, based on the total weight of thecarrier, and

(ii) the spectral patterns of the carrier observed by the nuclearmagnetic resonance analysis [²⁹Si-NMR (79.5 MHz)] are characterized by:

{circle around (1)} the combined area of peaks at −80 ppm, −86 ppm and−92 ppm being at least 15% of the total area of all peaks, and

{circle around (2)} the combined area of peaks at −80 ppm, −86 ppm, −92ppm and −98 ppm being at least 50% of the total area of all peaks.

The present invention relates thirdly to the method for hydrotreatinghydrocarbon oils with hydrogen under the hydrotreatment conditions inthe presence of the first or second catalyst of the present invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates the relationship between desulfurization activity andcontent of sulfur derived from dimethyl disulfide (DMDS) in the oilsamples, for the hydrotreating catalyst A₂ of the present invention(EXAMPLE X) and comparative hydrotreating catalyst A (COMPARATIVEEXAMPLE X).

FIG. 2 illustrates the relationship between tolerance to the inhibitingeffects by hydrogen sulfide and Brønsted acid (hereinafter referred toas the “B acid”.) content of the carrier, for the catalysts A₁, A₂, A₃and A₀ (EXAMPLE X) and comparative catalyst A (COMPARATIVE EXAMPLE X) ofdifferent B acid contents.

PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

The hydrotreating catalyst of the present invention comprises thecarrier having a Brønsted acid content of 50 μmol/g or more, whichsupports at least one active component (A) selected from the elements ofGroup 8 of the Periodic Table, and at least one active component (B)selected from the elements of Group 6 of the Periodic Table.

Carriers

The carrier materials useful for the present invention include alumina(Al₂O₃), silica (SiO₂), boric acid anhydride (B₂O₃), titania (TiO₂),zirconia (ZrO₂), iron(III)oxide (Fe₂O₃), beryllium oxide ((BeO), ceria(CeO₂), hafnia (HfO₂), magnesia (MgO), calcium oxide (CaO), zinc oxide(ZnO), thoria (ThO₂), chromium(III)oxide (Cr₂O₃), phosphorus oxides, anda combination thereof. The combinations include silica-alumina,silica-magnesia, silica-zirconia, silica-thoria, silica-beryllium oxide,silica-boria, silica-zinc oxide, alumina-zirconia, alumina-titania,alumina-boria, alumina-thoria, alumina-chromia, alumina-magnesia andtitania-zirconia. Clay minerals, in particular crosslinked intercalationminerals, can be also used. These include zeolite, montmorillonite,kaoline, halloysite, bentonite, attapulgite, bauxite, kaolinite, nacriteand anorthite. They may be used alone or in combination. For example, acombination of alumina-zeolite can be used. Of the carriers listedabove, particularly preferable ones are those based on silica-aluminaand silica-alumina-a third component. The third component is selectedfrom the group consisting of the above carrier materials except silicaand alumina, e.g., an alkali metal, alkaline earth metal, boria,titania, zirconia, iron(III)oxide, beryllium oxide, ceria, hafnia, zincoxide, thoria, chromium(III)oxide, phosphorus oxides, and zeolites andclay minerals. These silica-alumina-third component carriers includesilica-alumina-boria, silica-alumina-titania, silica-alumina-zirconia,silica-alumina-hafnia, silica-alumina-ceria, silica-alumina-sodiumoxide, silica-alumina-magnesia, silica-alumina-phosphorus oxides andsilica-alumina-zeolite.

It is important that the carrier for the hydrotreating catalyst of thepresent invention contains a B acid content of 50 μmol/g or more,preferably 80 μmol/g or more. Tolerance to the inhibiting effects byhydrogen sulfide (hereinafter referred to as the “tolerance to theinhibiting ettects by H₂S”) will be insufficient when the B acid contentis below 50 μmol/g, making the catalyst incapable of deeplyhydrotreating hydrocarbon oils. Hydrocarbon oils will be crackedexcessively, notably deactivating the catalyst, when it exceedsapproximately 2000 μmol/g.

B acid, defined as a proton donor, and a specific site on a solidsurface at which the acid donates a proton is referred to as a B acidsite. The catalyst exchanges electrons with ambient reactants at thissite to promote a variety of reactions. In this specification, B acidcontent of the carrier is defined as number of B acid sites per unitmass of the carrier (μmol/g).

It is possible to control B acid content of the carrier at 50 μmol/g ormore by controlling rate of dropping each carrier component solution tothe solvent during the carrier synthesis process, pH changes of thesynthesized solution, and rate of dropping water for the hydrolysis, inorder to control deposition rate of each component and improvedispersibility of each component in the carrier.

B acid content can be determined by various methods. It was determinedby the following series of steps for the carrier for the hydrotreatingcatalyst of the present invention:

A) Put 0.05 g of the sample in a glass tube or the like, and evacuatethe tube at 500° C. for 1 hour under a vacuum.

B) Pass 2,6-dimethyl pyridine (2,6-DMPy) into the evacuated glass tubekept at 200° C., to be adsorbed by the sample.

C) Pass nitrogen gas into the glass tube kept at 200° C. forapproximately 1 hour, after the adsorption step is over, to confirm thatno 2,6-DMPy is detected in the exhaust gas.

D) Heat the sample on which 2,6-DMPy is adsorbed at 5° C./min to 800°C., to desorb 2,6-DMPy, and determine quantity of 2,6-DMPy desorbed byan adequate method, e.g., gas chromatography, mass spectrometricanalysis or conductometric titration. Here, B acid content (μmol/g) isdefined as quantity of 2,6-DMPy desorbed from unit mass of the sample.

Specific surface area and pore volume of the carrier are not limited,but preferably 200 m²/g or more, more preferably 400 m²/g or more forthe former, and 0.4 ml/g to 1.2 ml/g for the latter, in order to securea specific B acid content and allow the catalyst to efficiently removethe difficult-to-remove sulfur compounds. For example, the carrier ofmesoporous silica-alumina (having pores of intermediate size) is morepreferable than that of silica-alumina (amorphous silica-alumia) havinga smaller specific surface area, because of the former's higher B acidcontent and more finely dispersed active components to give a largernumber of active sites.

The carriers of silica-alumina and silica-alumina-third component aredescribed below as the preferable ones for the hydrotreating catalyst ofthe present invention:

(Silica-alumina Carrier)

It is possible to secure a sufficient B acid content forhydrodesulfurization, hydrodenitrogenation, hydrodearomatization or thelike, when the silica-alumina carrier contains silica at 2 wt. % ormore, based on the total weight of the carrier, and a B acid content of50 μmol/g or more. The high silica-content carrier is preferable, e.g.,that contains silica at 10 wt. % or more, more preferably 20 wt. % ormore, still more preferably 30 wt. % or more, and still more preferably40 wt. % or more, in order to increase B acid content and improvetolerance of the catalyst to the inhibiting effects by H₂S for deepdesulfurization of sulfur-containing hydrocarbon oils. The silicacontent below 2 wt. % or above 95 wt. % will cause difficulties inmaking a practically useful, high-activity catalyst: essentially no Bacid sites express themselves at a silica content below 2 wt. %, andhydrocarbons will be excessively cracked at above 95 wt. %, to decreaseyield of the desired product.

The silica-alumina carrier having a specific B acid content for thehydrotreating catalyst of the present invention is obtained by finelydispersing silica in the carrier. It is therefore preferable for such acatalyst to have many aluminium atoms bonded to the silicon atomsregularly. It is also preferable that dispersibility of silica isspecified by coordination molphology between the silicon and aluminiumatoms via the oxygen atoms, determined by the nuclear magnetic resonanceanalysis. More concretely, the spectral peaks of silica-alumina obtainedby the ²⁹Si-NMR (79.5 MHz) method are processed for waveformdeconvolution by the least square adjustment method using the Gaussianfunction curve into those at −80 ppm, −86 ppm, −92 ppm, −98 ppm, −104ppm and −110 ppm, silica dispersibility being set for each peak andrepresented by peak area ratio. The above peak position is set based onbonding characteristic of silica, used as the waveform deconvolutioncondition for the ²⁹Si-NMR method, described later in EXAMPLES.

As a result, the coordination types between the silicon and aluminiumatoms are morphologically represented by the following formulae (I)through (V):

The silica-alumina carrier for the hydrotreating catalyst of the presentinvention has:

(i) a peak at −80 ppm, considered to represent the structure shown byformula (I) with the silicon atom bonded to 4 aluminium atoms(Si-4(OAl)), a peak at −86 ppm, considered to represent the structureshown by formula (II) with the silicon atom bonded to 3 aluminium atoms(Si-3(OAl)), and a peak at −92 ppm, considered to represent thestructure shown by formula (III) with the silicon atom bonded to 2aluminium atoms (Si-2(OAl)), having a combined area of at least 15% ofthe total area of all peaks (this ratio is hereinafter referred to asthe “NMR area ratio I”), and

(ii) the peaks described in the above (i) and a peak at −98 ppm,considered to represent the structure shown by formula (IV) with thesilicon atom bonded to one aluminium atom (Si-1(OAl)), having a combinedarea of at least 50% of the total area of all peaks (this ratio ishereinafter referred to as the “NMR area ratio II”).

It is necessary for the carrier to simultaneously satisfy the aboveconditions (i.e., NMR area ratio I of at least 15% and NMR area ratio IIof at least 50%), in order to realize the effects of the presentinvention: the good acidic conditions will not be formed unless theabove conditions are satisfied simultaneously, leading to decline of theactivity for hydrodesulfurization, hydrodenitrogenation,hydrodearomatization or the like.

The silica-alumina carrier having the finely dispersed silica componentand a high B acid content can be obtained by one of the methods (1)through (5), described below:

(1) Silicon alkoxide and aluminium alkoxide are mixed with a solutioncontaining at least one type of oxygenated, polar compound (e.g.,dihydric alcohol, aminoalcohol, ketoalcohol, diketone, ketocarboxylicacid, oxycarboxylic acid and dicarboxylic acid) at 10° C. to 200° C.,preferably 20° C. to 80° C., to form a homogeneous solution, to whichwater is added at the same temperature for hydrolysis, to totally gelthe homogeneous sol. The gel is then dried at 30° C. to 200° C., andcalcined at 200° C. to 1000° C., to remove the residual polarcompound(s) from the gel, in order to form the silica-aluminacomposition. The thermal treatment may be effected only with steam, oroptionally in an oxygen or air atmosphere.

Each of the above silicon alkoxide and aluminium alkoxide has preferablyan alkoxyl group having a carbon number of 1 to 10, preferably 1 to 5.More concretely, the silicon alkoxides useful for the present inventioninclude tetramethoxysilane (Si(OCH₃)₄), tetraethoxysilane (Si(OC₂H₅)₄),tetraisopropoxysilane ((Si(i-OC₃H₇)₄) and tetra-tertiary-butoxysilane(Si(t-OC₄H₉)₄), and the aluminium alkoxides include aluminiumtrimethoxide (Al(OCH₃)₃), aluminium triethoxide (Al(OC₂H₅)₃), aluminiumtriisopropoxide (Al(i-OC₃H₇)₃) and aluminium tributoxide (Al(OC₄H₉)₃).Concentration of each of these compounds can be optionally set, but thesilicon alkoxide/aluminium alkoxide ratio is set to give a desiredsilicon content (e.g., 30 wt % and more) in the silica-alumina carrier.The polar compound is used in a molar ratio of 0.1 to 20, preferably 0.1to 15, to the silicon alkoxide and aluminium alkoxide. Water forhydrolysis in the gelation process is used in a molar ratio of 0.5 to50, preferably 1 to 40, to the silicon alkoxide and aluminium alkoxide.The hydrolysis process may be accelerated by a water-soluble hydrolysisaccelerator, e.g., inorganic acid, organic acid, inorganic alkali andorganic alkali, in particular organic acid, e.g., formic acid or oxalicacid; and organic alkali, e.g., amine or aminoalcohol.

(2) This method uses metallic alkoxides, like the method (1) above, butno oxygenated, polar compound. This method falls into the following 3sub-groups {circle around (1)} to {circle around (3)}:

{circle around (1)} A mixture of an aluminium alkoxide and water isheated, to form a white, turbid sol. A mineral acid, e.g., nitric acidor hydrochloric acid, is added and the solution thus prepared is keptacidic, preferably at pH of 2 to 3, to form the clear sol. Then, asilicon alkoxide or another type of silicon compound (e.g., siliconhalide) is added to the clear sol for gelation to form thesilica-alumina gel, where quantity of the silicon compound added isadjusted to give a desired silicon content (e.g.,30 wt. % or more) inthe silica-alumina carrier. The gel is dried and calcined into thesilica-alumina composition for the carrier. The drying and calcinationmethods will be similar to those for the above method (1).

{circle around (2)} This method is similar to the above method {circlearound (1)}, except that the silicon compound and aluminium compound areadded in this order. Water is added to a silicon alkoxide to form aclear sol, to which an aluminium compound (e.g., aluminium alkoxide,aluminium sulfate, aluminium nitrate or aluminium hydroxide) is added,to turn the sol into gel. It is dried and calcined in a manner similarto those for the above method, to form the silica-alumina composition.

{circle around (3)} This method uses a composite alkoxide, where analuminium alkoxide is mixed with cyclohexane, to which trimethylsilylacetate (CH₃COOSi(CH₃)₃) mixed with cyclohexane is dropped under heatingwith reflux, to form the composite silicon-aluminium alkoxide. Thecomposite alkoxide is hydrolyzed into the gel, which is dried andcalcined by the common methods into the silica-alumina composition forthe carrier.

(3) The silica-alumina carrier for the hydrotreating catalyst of thepresent invention can be also prepared by the so-called coprecipitation.This method uses No.3 water glass as specified by the JapaneseIndustrial Standards (JIS) (hereinafter referred to as the “No.3 waterglass”) as the silica source, and sodium aluminate as the aluminasource. They are homogeneously mixed with each other at a pH of around8, to which an aqueous solution of mineral acid (e.g., nitric acid) isadded dropwise, to coprecipitate them. The coprecipitation can be alsoeffected by adding aqueous solution of water glass, aqueous solution ofsodium aluminate and nitric acid simultaneously to water. Quantity ofthe silica source is set to give a desired silica content in thecarrier.

A silicate of alkali metal as the silica source can be used as theaqueous solution containing the water-soluble salt at 0.1 mols to 10mols, preferably 0.3 mols to 5 mols, and sodium aluminate as the aluminasource can be used as the aqueous solution containing the water-solublesalt at 0.1 mols to 4 mols, preferably 0.3 mols to 2 mols.

(4) The silica-alumina carrier for the hydrotreating catalyst of thepresent invention can be also prepared by deposition of silica hydrategel over alumina hydrate gel. The alumina source useful for the presentinvention includes a water-soluble, acidic or alkaline aluminiumcompound, e.g., sulfate, chloride or nitrate of aluminium; sodiumaluminate; or aluminium alkoxide. The silica source is a water-solublesilicon compound, e.g., silicate of alkali metal (e.g., No.3 waterglass, having an Na₂O/SiO₂ ratio of 1:2 to 1:4), tetraalkoxysilane, ororthosilicate ester. These aluminium and silicon compounds are used inthe form of aqueous solutions. Their concentrations can be optionallyset, but concentration of the aluminium compound is set at 0.1 mols to 4mols, and that of the silicon compound is set to give a desired silicacontent in the carrier.

An example of deposition of the silica-alumina composition is describedbelow:

Pure water is heated at around 40° C. to 90° C., in which sodiumaluminate is dissolved, and the solution is kept at the same temperatureand a pH level of 10 to 12. Then, nitric acid is added to the abovesolution to adjust its pH level at 8.5 to 9.5, and the solution is agedat the same temperature for 1.5 to 3 hours, to precipitate the aluminahydrate.

Next, an aqueous solution of sodium silicate (e.g., No.3 water glass) isadded little by little to the above alumina hydrate, to which nitricacid is added to adjust the solution at a pH level of 8 to 10, and thesolution is aged at around 50° C. to 90° C. for 1 hour to 3 hours, todeposite the silica hydrate over the alumina hydrate. Quantity of sodiumsilicate to be used is set to give a desired silica content (30 wt. % ormore) in the silica-alumina carrier. The precipitates are separated fromthe aqueous solution by filtration, washed with a solution of ammoniumcarbonate and water, and dried and calcined to form the silica-aluminacomposition for the carrier. The drying is effected at normaltemperature to around 200° C. in the presence or absence of oxygen, andthe calcination is effected at around 200° C. to 800° C. in the presenceof oxygen.

(5) The silica-alumina carrier with finely dispersed silica for thehydrotreating catalyst of the present invention can be also prepared byvapor-phase deposition, in which silicon alkoxide is deposited over analumina carrier produced by the conventional method. It can be alsoproduced by depositing aluminium oxide over a silica carrier by thevapor-phase deposition method.

(Silica-alumina-third Component Carrier)

Next, the silica-alumina-third component carrier is described.

The silica-alumina-third component carrier for the hydrotreatingcatalyst of the present invention comprises silica, alumina and a thirdcomponent. It must have an NMR area ratio I of at least 15% and NMRratio II of at least 50%, as is the case of the silica-alumina carrierabove. The silica content is 2 wt. % or more, preferably 10 wt. % ormore, more preferably 20 wt. % or more, based on the total weight of thecarrier composition. The third components useful for the presentinvention include an alkali metal, an alkaline earth metal, boria,titania, zirconia, iron(III)oxide, ceria, hafnia, thoria, berylliumoxide, zinc oxide, chromium(III)oxide, phosphorus oxides, zeolites andclay minerals. These silica-alumina-third component carriers fall intothe following three general categories by type of the third component.

The third component A has an alkali metal or alkaline earth metal(hereinafter referred to as the “alkali metal component or the like,” asrequired), the third component B includes boria, titania, zirconia,iron(III)oxide, ceria, hafnia, thoria, zinc oxide, chromium(III)oxide,zeolites and clay mineral (hereinafter referred to as the “boria or thelike,” as required), and the third component C has phosphorus oxides.

(1) Silica-alumina-third Component A Carrier

The silica-alumina-third component A carrier comprises silica, aluminaand the alkali metal component or the like, and has a Brønsted acidcontent of 50 μmol/g or more. The alkali metal component or the like isat least one type of component selected from the group consisting ofalkali metal and alkaline earth metal components. More concretely, thealkali metals include sodium, potassium and lithium, and the alkalineearth metals include calcium, magnesium, strontium and barium, normallyused in the form of oxides.

The silica-alumina-third component A carrier is characterized bydiminished or removed strong B acid content in the B acid distributionby including the alkali metal component or the like. More concretely,the B acid content in a range from 600° C. to 800° C. in the2,6-DMPy-TPD profile accounts for 10% or less, preferably 7% or less, ofthe total B acid content. The carrier having the above B aciddistribution provides the hydrotreating catalyst with favorable effects,such as excellent tolerance to the inhibiting effects by H₂S, notablycontrolled coking of hydrocarbons, and excellent activity maintenance.

Content of the alkali metal component or the like is 0.01 wt. % to 10wt. %, preferably 0.05 wt. % to 8 wt. % as the oxide, based on the totalweight of the carrier composition. The effects on the B aciddistribution is insufficient at below 0.01 wt. %, and the effects ofremoving strong B acid sites are not expected much, accelerating cokingof hydrocarbons and declining catalyst activity. At above 10 wt. %, onthe other hand, the effects of B acid no longer increase with itscontent.

Methods for adding a third component to the hydrotreating catalyst ofthe present invention using the silica-alumina-third component A carrierare not limited, and it can be added by a common method. Some of thesemethods are described below:

{circle around (1)} A silica-alumina carrier is impregnated first withthe alkali metal component or the like, using its solution, and thenwith the active components.

{circle around (2)} A silica-alumina carrier is impregnated first withthe active components and then with the alkali metal component or thelike, using its solution.

{circle around (3)} A silica-alumina carrier is impregnatedsimultaneously with the alkali metal component or the like and activecomponents, using a mixed solution of these components.

{circle around (4)} The alkali metal component or the like is added tothe carrier stocks during the carrier production stage, i.e., when thesilica-alumina carrier is produced using their alkoxide solutions, agiven quantity of sodium methoxide, calcium methoxide or barium ethoxideis added to the alkoxide solutions.

(2) Silica-alumina-third Component Carrier B

The silica-alumina-third component B carrier comprises silica, aluminaand the third component B below described, and has a Brønsted acidcontent of 50 μmol/g or more.

The third component B is optionally selected from the group consistingof boria, titania, zirconia, iron(III) oxide, ceria, halfnia, thoria,beryllium oxide, zinc oxide, chromium(III) oxide, and zeolite and clayminerals (referred to as the “metallic component of boria or the like”,as required).

The third component B works to increase total B acid content, morenotably B acids of medium to weak in strength. More concretely, thestrong B acid in a range from 600° C. to 800° C. in the 2,6-DMPy-TPDprofile shows little increase, whereas weak to medium B acids in a rangefrom 200° C. to 400° C. and from 600° C. to 800° C. show notableincreases. Therefore, the third component B can provide a sufficient Bacid content for desulfurization reactions in the presence of hydrogensulfide, while controlling coking of the hydrocarbons.

Content of the metallic component of boria or the like is 0.01 wt. % to50 wt. %, preferably 0.05 wt. % to 40 wt. %, more preferably 0.1 wt. %to 30 wt. % as the oxide, based on the total weight of the carriercomposition. The effects on the B acid distribution is insufficient atbelow 0.01 wt. %, and the effects of B acid no longer increase with itscontent at above 50 wt. %.

Methods for producing the silica-alumina-third component B carrier arenot limited, and it can be produced by a common method. For example, themetallic component of boria or the like may be added to the carrierstocks during the carrier production stage, or added to the producedcarrier from the liquid or vapor phase. In the liquid-phase process, thecarrier may be impregnated with boria or the like by dropping onto thesilica-alumina carrier (Pore-Filling method). Some of the methods forproducing the carrier with finely dispersed silica by adding boria orthe like to the carrier stocks during the carrier production stage aredescribed below:

<1>A solution of alkoxide or another compound as the third component Bis added to silicon alkoxide and aluminium alkoxide during the carrierproduction stage. Examples of the alkoxide as the third component Binclude boron methoxide, boron triethoxide, titanium tetraethoxide,titanium tetraisopropoxide, zirconium tetraethoxide, zirconiumtetra-n-propoxide, zirconium tetra-sec-butoxide and hafniumtetraethoxide, which can be optionally used. The composition of siliconalkoxide, aluminium alkoxide and other metal alkoxide is prepared insuch a way to give desired contents of silica and the third component Bin the whole carrier composition. Quantities of an oxygenated, polarcompound and water for hydrolysis in the gelation process are alsodetermined to satisfy the above objectives.

<2> The method falling into this category uses the metal alkoxides, butno oxygenated, polar compound. It is further subdivided into the methods{circle around (1)} to {circle around (3)} for the silica-aluminacarrier described earlier. In each case, the carrier can be prepared bythe method similar to that for the silica-alumina carrier describedearlier by adding an alkoxide of, e.g., boron, titanium, zirconium orhafnium, or a water-soluble compound thereof, to silicon or aluminiumalkoxide.

<3> The silica-alumina-third component B carrier for the presentinvention can be also prepared by coprecipitation. The carrier can beprepared by the method similar to that for the silica-alumina carrierdescribed earlier by adding a given quantity of the above metalliccomponent in the form of a water-soluble compound, e.g., triethylborate. Quantities of the silica source and the metallic component ofboria or the like are set to give desired silica and the metalliccomponent contents in the silica-alumina-third component B carrier. Itis preferable to use the water-soluble salt of the metallic componentsource in a range from 0.01 mols to 2 mols, for gel precipitation withsilica and alumina.

<4> The silica-alumina-third component B carrier can be also prepared bydeposition, where the hydrate gels of silica and metallic component aredeposited over the alumina hydrate gel. It can be prepared by the methodsimilar to that for the silica-alumina carrier described earlier byadding the above metallic component in the form of a water-solublecompound, e.g., triethyl borate.

(3)Silica-alumina-third Component Carrier C

The silica-alumina-third component C carrier comprises silica, aluminaand the third component C below described, and has a Brønsted acidcontent of 50 μmol/g or more.

The third component C is a phosphorus compound, such as phosphoric acid,phosphorous acid, hydrophosphorous acid, phosphomolybdic acid,phosphotungstic acid or ammonium phosphotungstate, normally added to thesilica-alumina composition in the form of an oxide. Content of thephosphorus compound is 0.01 wt. % to 10 wt. % as the oxide, based on thetotal weight of the carrier, preferably 0.05 wt. % to 8 wt. %. Thehydrotreating catalyst on the silica-alumina-phosphorus componentcarrier shows improved tolerance to the inhibiting effects by nitrogencompounds, and hence improved desulfurization activity. It isconsidered, although not fully substantiated, that addition of thephosphorus compound changes the active site structure. Virtually noimprovement of the tolerance to the inhibiting effects by nitrogencompounds nor improvement of the desulfurization acitivity is observedat a phosphorus compound content below 0.01 wt. %, and the effects ofthe phosphorus compound no longer increase with its content at above 10wt. %.

Methods for producing the silica-alumina-phosphorus component carrierare not limited. For example,:

{circle around (1)} The silica-alumina carrier is impregnated first witha phophoric acid solution alone and then with the active components.

{circle around (2)} The silica-alumina carrier is impregnated first withthe active components and then with a phophoric acid solution.

{circle around (3)} The silica-alumina carrier is impregnated with amixed solution of the phosphorus component and active components.

{circle around (4)} The silica-alumina carrier is impregnated with aheteropoly acid of the active components and phosphorus component (e.g.,phosphomolybdic acid).

{circle around (5)} The phosphorus compound is added to the carrierstocks during the carrier production stage, i.e, when the silica-aluminacarrier is produced using their alkoxide solutions, an alkoxide of thephosphorus compound (e.g., trimethyl phosphate) is used.

The silica-alumina-third component C carrier thus prepared must have a Bacid content of 50 μmol/g or more, preferably 80 μmol or more. Thehydrotreating catalyst on the above carrier must have the specific NMRarea ratios described earlier.

Hydrotreating Catalyst

The active component (A) for the hydrotreating catalyst of the presentinvention is at least one active component selected from the elements ofGroup 8, such as iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru),rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum(Pt), preferably cobalt, nickel, ruthenium, rhodium, palladium, iridiumand platinum. They may be used alone or in combination.

Content of the active component (A) is 0.05 wt. % to 20 wt. % as theoxide(s), based on the total weight of the catalyst composition,preferably 0.1 wt. % to 15 wt. %. At below 0.05 wt. %, quantity of theactive component is insufficient for the interactions with B acid,causing various problems, such as insufficient tolerance to theinhibiting effects by H₂S and accompanied difficulty in deepdesulfurization of sulfur-containing hydrocarbon oils, and insufficientcatalyst activity for hydrodenitrogenation, hydrocracking,hydrodearomatization, hydrofining or the like. At above 20 wt. %, on theother hand, the active component cannot be finely dispersed on thecarrier, decreasing number of the active sites, which, in turn, declinesthe catalyst activity for hydrotreatment, e.g., hydrodesulfurization andhydrodenitrogenation.

The active component (B) for the hydrotreating catalyst of the presentinvention is at least one active component selected from the elements ofGroup 6, such as chromium (Cr), molybdenum (Mo), and tungsten (W),preferably molybdenum and tungsten. They may be used alone or incombination.

Content of the active component (B) is 5 wt. % to 40 wt. % as theoxide(s), based on the total weight of the catalyst composition,preferably 8 wt. % to 30 wt. %. At below 5 wt. %, number of the activesites is insufficient to give the high activity for hydrotreatment,e.g., hydrodesulfurization and hydrodenitrogenation. At above 40 wt. %,on the other hand, the active component cannot be finely dispersed onthe carrier, decreasing number of the active sites, which, in turn,makes it difficult to deeply desulfurize sulfur-containing hydrocarbonoils and declines the catalyst activity for hydrotreatment, e.g.,hydrodenitrogenation.

The concrete combinations of the active components (A) and (B) forhydrotreatment, e.g., hydrodesulfurization and hydrodenitrogenation, ofsulfur-containing hydrocarbon oils include cobalt-molybdenum,nickel-molybdenum, nickel-tungsten, cobalt-nickel-molybdenum andcobalt-nickel tungsten.

Each of the above active components can be incorporated with a Group 7element (e.g., manganese), Group 12 element (e.g., zinc) and Group 14element (e.g., tin and germanium).

Methods for producing the hydrotreating catalyst of the presentinvention are not limited, and a known method can be used. For example,nitrates, acetates, formates, ammonium salts, phosphates and oxides of aGroup 8 element as the active component (A) and Group 6 element as theactive component (B) are dissolved in a solvent to prepare the solutionfor impregnation. This solution is then incorporated with an organicacid, e.g., citric, tartaric, malic, acetic or oxalic acid, and adjustedat a pH level of around 9 with ammonia water. The resultant solutionhaving a pH level of around 9, is added, with stirring, to the carrierdrop by drop for the impregnation.

The solvents are not limited, and various ones can be used. Theseinclude water, ammonia water, alcohols, ethers, ketones and aromaticcompounds, preferably water, ammonia water, acetone, methanol,n-propanol, i-propanol, n-butanol, i-butanol, hexanol, benzene, toluene,xylene, diethyl ether, tetrahydrofuran and dioxane, more preferablywater.

The mixing ratio of the solvent and the both active components in thesolution for impregnation and quantity of impregnation into the carrierare not limited, and can be set to give desired contents of the activecomponents in the calcined catalyst, in consideration of easiness of theimpregnation and drying and calcination processes.

The carrier impregnated with the active components is then formed into adesired shape by tablet making, extrusion, rotational granulation or thelike, dried by wind and/or hot wind, heating or freeze-drying, andcalcined at 400° C. to 600° C. for 3 hours to 5 hours. The oxides of theactive components supported by the carrier will agglomerate as thecrystals at an excessively high calcination temperature, decreasingsurface area and pore volume, and hence catalyst activity. On the otherhand, ammonia, acetate ions or the like contained in the supportedactive components may not be sufficiently removed at an excessively lowcalcination temperature, with the result that the active sites on thecatalyst surface may not be sufficiently exposed, also possibly causingactivity decline. It is preferable to effect the calcination processgradually.

The active components for the hydrotreating catalyst of the presentinvention may be added to the carrier separately in two steps. Forexample, the component (B) and (A) are added in this order, or thisorder may be reversed. It is preferable to add the component (A) to thecarrier after the latter is immersed in ammonia water in the first step,and then the component (B) is added in the second step, viewed fromsecuring high desulfurization activity.

The hydrotreating catalyst of the present invention preferably has aspecific surface area of around 200 m²/g or more, and total pore volumeof 0.4 ml/g or more. It is cylindrical, granular, tablet or in anyshape, preferably 0.5 mm to 3 mm in size.

The hydrotreating catalyst of the present invention may be used after itis mixed with another type of hydrotreating catalyst, as required. Ratioof the hydrotreating catalyst of the present invention is 5 wt. % to 50wt. % based on the total mixture, preferably 10 wt. % to 40 wt. %. Atbelow 5 wt. %, insufficient number of the spill-over hydrogen formingsites may result, which may possibly cause insufficient tolerance of themixed catalyst to the inhibiting effects by H₂S, making it difficult todeeply hydrodesulfurize sulfur-containing hydrocarbon oils anddecreasing the catalyst activity for other types of hydrotreatment. Atabove 50 wt. %, insufficient number of the active desulfurization sitesmay result, possibly making it difficult to deeply hydrodesulfurizesulfur-containing hydrocarbon oils and decreasing the catalyst activityfor other types of hydrotreatment. As the another type of hydrotreatingcatalyst here, a known hydrotreating catalyst may be used.

Method of Hydrotreatment

Next, the method for hydrotreating hydrocarbon oils in the presence ofthe hydrotreating catalyst of the present invention is described.

The method of hydrotreatment of the present invention includes all ofthe reactions, e.g., hydrodesulfurization, hydrodenitrogenation,hydrocracking, hydrodearomatization, hydroisomerization and hydrofining,occurring when hydrocarbon oils are brought into contact with hydrogenin the presence of the hydrotreating catalyst of the present inventionunder hydrotreatment conditions. The hydrotreatment conditions can beoptionally selected for the desired reactions.

The hydrocarbon oils which can be treated by the method of the presentinvention are not limited, and can be optionally selected from petroleumfractions, e.g., atmospheric and vacuum distillates, and crackedfractions, in particular atmospheric and vacuum gas oils, and gas oilsfrom cracking processes, e.g., catalytic cracking, thermal cracking andcoking. Vacuum gas oil contains a fraction boiling at about 370° C. to610° C., obtained by distilling atmospheric residua under a vacuum andknown to contain significant contents of sulfur, nitrogen and metals.For example, vacuum gas oil from a Middle Eastern crude contains sulfurand nitrogen at about 2 wt. % to 4 wt. % and 0.05 wt. % to 0.2 wt. %,respectively. Coker gas oil contains a fraction obtained by coking ofresidua and has a boiling point of about 200° C. or higher.

The reaction conditions under which sulfur-containing hydrocarbon oilsare hydrodesulfurized optionally selected for specific conditions, e.g.,feedstock type, and desired desulfurization and denitrogenation levels.They are generally in the following ranges; reaction temperature: 200°C. to 500° C., reaction pressure: 5 kg/cm² to 200 kg/cm²,hydrogen/feedstock ratio: 50 l/l to 4000 l/l, and liquid hourly spacevelocity (LHSV): 0.05 h⁻¹ to 10h ⁻¹. Content of hydrogen inhydrogen-containing gas may be 60% to 100%. More concretely, deephydrodesulfurization of sulfur-containing hydrocarbon oils does not needparticularly severe reaction conditions but proceeds under normalhydrodesulfurization conditions, e.g., reaction temperature: 200° C. to500° C., preferably 250°C. to 400° C., reaction pressure: 5 kg/cm² to 60kg/cm², liquid hourly space velocity: 0.05 h⁻¹ to 5 h⁻¹ andhydrogen/feedstock ratio: 50 l/l to 100 l/l Difficult-to-remove sulfurcompounds, e.g., 4-methyl dibenzothiophene and 4,6-dimethyldibenzothiophene, can be easily removed under the above reactionconditions, even in the presence of hydrogen sulfide.

The hydrotreating catalyst of the present invention can be used for anyhydrodesulfurization reactor type, e.g., fixed, fluidized or moving bedreactor. However, a fixed bed reactor is particularly preferable fromequipment and operation considerations. The hydrodesulfurization usingthe hydrotreating catalyst of the present invention can be effected bytwo or more reactors connected to one another. It is preferable topresulfide the active components of the hydrotreating catalyst of thepresent invention, before a hydrocarbon oil is passed over the catalystunder the hydrotreatment conditions.

The present invention is more concretely described by the followingembodiments, which by no means limit the present invention.

(1) A hydrotreating catalyst comprising a silica-alumina carrier havinga silica content of 10 wt. % or more and a B acid content of 50 μmol/gor more, which (A) supports at least one active component (A) selectedfrom the elements of Group 8, and at least one active component (B)selected from the elements of Group 6 (hereinafter referred to as the“active component”).

(2) A hydrotreating catalyst comprising a carrier composed of silica,alumina and a third component of an alkali metal and/or alkaline earthmetal, and having a B acid content of 50 μmol/g or more, which supportsthe above active components (A) and (B),

wherein, the content of silica is 10 wt. % or more, based on the totalweight of the carrier, and the content of the alkali metal and/oralkaline earth metal components is 0.01 wt. % to 10 wt. % as the oxide,also based on the total weight of the carrier.

(3) A hydrotreating catalyst of (2), wherein the B acid content in arange from 600° C. to 800° C. in the 2,6-DMPy-TPD profile accounts for10% or less of the total B acid content.

(4) A hydrotreating catalyst comprising a carrier composed of silica,alumina and a metal component of boria or the like, and having a B acidcontent of 50 μmol/g or more, which supports the above active components(A) and (B), wherein, content of silica is 10 wt. % or more, based onthe total weight of the carrier, and

content of the metal component of boria or the like is 0.01 wt. % to 50wt. % as the oxide, also based on the total weight of the carrier.

(5) A hydrotreating catalyst comprising a carrier composed of silica,alumina and a phosphorus component, and having a B acid content of 50μmol/g or more, which supports the above active components (A) and (B),wherein, the content of silica is 10 wt. % or more, based on the totalweight of the carrier, and the content of the phosphorus component is0.01 wt. % to 10 wt. % as the oxide, also based on the total weight ofthe carrier.

(6) The silica-alumina or silica-alumina-third component carrier, havinga B acid content of 50 μmol/g or more, for the above hydrotreatingcatalyst.

(7) Method for hydrotreatment of sulfur-containing hydrocarbon oilsusing the catalyst or carrier, described in (1) through (6).

EFFECTS OF THE PRESENT INVENTION

In accordance with teaching of the present invention, described above indetail and concretely, the hydrotreating catalyst of the presentinvention exhibits improved tolerance to the inhibiting effects by H₂Sand high desulfurization activity by supporting at least one activecomponent (A) selected from the elements of Group 8, and (B) at leastone active component (B) selected from the elements of Group 6 on thecarrier having a Brønsted acid content of 50 μmol/g or more, inparticular the silica-alumina or silica-alumina-third component carrierfinely dispersing silica and having Brønsted acid content of 50 μmol/gor more. Use of the hydrotreating catalyst of the present inventionallows deep desulfurization, e.g., decreasing sulfur content to 0.05 wt.% or less, of sulfur-containing hydrocarbon oils, in particular thosecontaining a high content of sulfur, e.g., light gas oil (LGO) andvacuum gas oil (VGO). The hydrotreating catalyst of the presentinvention is also useful for hydrodenitrogenation, hydrocracking,hydrodearomatization, hydrofining or the like.

PREFERRED EMBODIMENTS

The present invention is described more concretely by the followingEXAMPLES and COMPARATIVE EXAMPLES, which by no means limit the presentinvention:

The sample oils used in EXAMPLES and COMPARATIVE EXAMPLES are describedbelow:

Sample Oils

A total of 7 types of sample oils, shown in Table 1, were prepared usingn-hexadecane (n-C₁₆), treated light gas oil (LGO-T), 4,6-dimethyldibenzothiphene (4,6-DMDBT), dimethyl disulfide (DMDS) and quinoline.LGO-T contains 0.29 wt. % of sulfur, mostly derived from 4,6-DMDBT.

4,6-DMDBT is a model of difficult-to-remove sulfur compound present inhydrocarbon oils, and DMDS is a model of compound which generateshydrogen sulfide.

TABLE 1 Sample Oils 1 2 3 4 5 6 7 Composition (wt. %) n-C₁₆ 99.70 98.9297.72 93.82 93.75 — 99.63 LGO-T — — — — — 98.47 — 4,6-DMDBT 0.30 0.300.30 0.30 0.30 — 0.30 DMDS — 0.78 1.98 5.88 5.88 1.47 — Quinoline — — —— 0.07 0.06 0.07 Sulfur content (wt. %) 0.05 0.58 1.40 4.05 4.05 1.050.05 DMDS-derived sulfur 0 0.53 1.35 4.00 4.00 1.00 0 content (wt. %)n-C₁₆: n-hexadecane LGO-T: treated light gas oil (sulfur content: 0.29wt. %) 4,6-DMDBT: 4,6-dimethyl dibenzothiophene DMDS: dimethyl disulfide

EXAMPLE X

Catalysts A₁, A₂ and A₃

80.13 g of aluminium triisopropoxide [Al(i-OC₃H₇)3] (produced by SoekawaRika) was mixed and reacted with 788 ml of 2-methylpentane-2,4-diol[CH₃CH(OH)CH₂C(CH₃)₂OH] (produced by Tokyo Kasei Kogyo), with stirring,at 80° C. for 5 h, to which 69.3 g of tetraethoxysilane [Si(OC₂H₅)₄](Koso Kagaku Yakuhin) was added to be further reacted with the above at80° C. for 12 h, with stirring. Then, 225.8 ml of water was dropped tothe above effluent at 1 ml/min, for hydrolysis at 80° C. On completingthe hydrolysis, the product was dried at 90° C., and calcined at 600° C.for 5 h in a flow of air, to prepare the silica-alumina composition. Itcontained silica at 50 wt. %.

Next, 5.50 g of nickel nitrate [Ni(NO₃)₂.6H₂O] (produced by Koso KagakuYakuhin), 6.93 g of ammonium molybdate [(NH₄)₆Mo₇O₂₄.4H₂O] (produced byKoso Kagaku Yakuhin), and 3.1 g of citric acid were dissolved in 40.5 gof a mixed solution of concentrated ammonia water and pure water, toprepare the solution for impregnation. Composition of the mixed solutionof concentrated ammonia water and water was set to adjust the solutionfor impregnation at pH=9, after it dissolved all of the above solutes.The above silica-alumina composition was coimpregnated with the abovesolution by the Pore Filling method, dried at 110° C. for 48 h, formedinto a disk shape and calcined at 500° C. for 3 h in a flow of air, toprepare Catalyst A₂.

The silica-alumina compositions containing silica at 20 wt. % and 95 wt.% were prepared in the same manner as the above, except the ratio ofaluminium triisopropoxide and tetraethoxysilane was changed. They wereused to prepare Catalysts A₁ and A₃ containing silica at 20 wt. % and 95wt. %, respectively, also in manner similar to the above. Each of thehydrotreating Catalysts A₁, A₂ and A₃ contained nickel oxide (NiO) andmolybdenum oxide (MoO₃) at 3 wt. % and 12 wt. %, respectively.

Catalysts A₀

Catalyst A₀ was prepared in the same manner as the above, except that amesoporous silica-alumina composition was used in place of thesilica-alumina composition of Catalysts A₃ described above. The contentof silica in the porous silica-alumina was 95 wt. %. This catalystcontained nickel oxide (NiO) and molybdenum oxide (MoO₃) at 3 wt. % and12 wt. %, respectively.

The mesoporous silica-alumina composition was prepared by the followingprocedure. 170.11 g of water glass No. 3 (produced by Koso KagakuYakuhin), 6.7 g of sodium aluminate (NaAlO₂) (produced by Koso KagakuYakuhin), 75.5 g of n-hexadecyltrimethyl ammonium bromide[(C₁₆H₃₃N(CH₃)₃Br] (produced by Tokyo Kasei Kogyo) were dissolved in975.57 g of water. This solution was adjusted at pH=10 with 20.4 g ofsulfuric acid (H₂SO₄). It was then treated under hydrothermalconditions, with stirring, at 120° C. for 82 h in an autoclave. Theproduct was washed with water, dried at 110° C. for 16 h, and calcinedat 600° C. for 5 h, to prepare the mesoporous silica-aluminacomposition. It showed a different crystal structure from that of thesilica-alumina composition (e.g., with respect to specific surface areaand average pore diameter).

Comparative Example X

Comparative Catalyst A

Comparative Catalyst A was prepared in the same manner as that forCatalyst A₂, except that alumina (produced by Nippon Ketjen) was used inplace of the silica-alumina composition. This catalyst contained nickeloxide (NiO) and molybdenum oxide (MoO₃) at 3 wt. % and 12 wt. %,respectively.

Catalyst A₁, Catalyst A₂, Catalyst A₃, Catalyst A₀ and ComparativeCatalyst A contained B acid at 50 μmol/g, 150 μmol/g, 85 μmol/g, 180μmol/g and 0 μmol/g, respectively. B acid content was determined by themethod described earlier. Evacuation of the tube was effected by avacuum device produced by Shinku Kiko), and quantity of 2,6-DMPy wasdetermined by conductometric titration. Properties of these catalystsare given in Table 2.

TABLE 2 EXAMPLE X Catalyst A₁ Catalyst A₂ Catalyst A₃ Catalyst A₀Comparative Catalyst A Carrier · Type of carrier Silica-AluminaSilica-Alumina Silica-Alumina Mesoporous Silica-Alumina Alumina ·Specific surface area (m²/g) 670 660 400 970 200 · Silica content (wt.%) 20 50 95 95 0 · B acid content (μmol/g) 50 150 85 180 0 Quantities ofsupported active components NiO (wt. %) 3 3 3 3 3 MoO₃ (wt. %) 12 12 1212 12 B acid content: Br φnsted acid content

Desulfurization Test Method

Each hydrotreating catalyst prepared was tested for its desulfurizationactivity using the sample oils shown in Table 1 by a flow type autoclave(inner diameter: 25.4 mm and length: 100 mm). Table 3 gives thedesulfurization test conditions. Each catalyst was milled to have adiameter of 0.6 to 0.8 mm, and 0.5 g of the milled catalyst was chargedinto the autoclave. The sample oil was treated over the catalyst untilsulfur content attained an equilibrium level, which took about 1 h, anddesulfurization rate (%) as the catalyst activity was determined fromthe equilibrium sulfur content. The tolerance of the inhibiting effectsby H₂S with Sample Oil 2 is defined as the desulfurization activity withthat Sample Oil 2 relative to the activity with Sample Oil 1 (n-C₁₆incorporated only with 4,6-DMDBT) under the desulfurization testconditions shown in Table 3. Thus, the tolerance of the inhibitingeffects by H₂S was determined with Sample Oils 3 to 7. Thedesulfurization test was also conducted separately with n-C₁₆incorporated only with DMDS, which confirmed that DMDS was thermallydecomposed almost completely and sulfur contained therein was totallyconverted into H₂S.

TABLE 3 Desulfurization Test Conditions I II Sample oil flow rate(ml/min) 0.15 0.05 Reaction temperature (° C.) 310 340 Hydrogen partialpressure (MPa) 0.9 0.9 Hydrogen flow rate (NL/L) 400 400

EXAMPLE X-1

Sample Oils 1 to 4, shown in Table 1, were desulfurization-tested in thepresence of Catalyst A₂ under the desulfurization test conditions Ishown in Table 3. The test results are given in FIG. 1, which shows therelationship between the desulfurization activity and content ofDMDS-derived sulfur in the sample oil.

Comparative Example X-1

The desulfurization test was conducted under the same conditions asthose for EXAMPLE X-1 except that Comparative Catalyst A was used inplace of Catalyst A₂. The test results are also given in FIG. 1, whichshows the relationship between the desulfurization activity and contentof DMDS-derived sulfur in the sample oil.

EXAMPLE X-2

The desulfurization tests were conducted with Sample Oil 5 shown inTable 1, which was passed over Catalyst A₁, Catalyst A₂, Catalyst A₃,Catalyst A₀ and Comparative Catalyst A under the desulfurization testconditions II shown in Table 3. These catalyst samples had different Bacid contents. The test results are given in FIG. 2, which shows therelationship between the tolerance to the inhibiting effects by H₂S andB acid content.

EXAMPLE X-3

The desulfurization test was conducted with Sample Oil 5 shown in Table1, which was passed over Catalyst A₀ under the desulfurization testconditions II shown in Table 3. The test results are given in Table 4.The test was also conducted over Catalyst A₃, which contained the samesilica content (95 wt. %) and was on the silica-alumina (amorphoussilica-alumina) carrier, under the same conditions. The test results arealso given in Table 4, for comparison.

TABLE 4 Catalyst A₀ Catalyst A₃ Carriers • Type Mesoporous Silica-silica-alumina alumina • Specific surface area (m²/g) 970 400 • Silicacontent (wt. %) 95 95 • B acid content (μmol/g) 180 85 Contents of thesupported active components • NiO (wt. %) 3 3 • MoO₃ (wt. %) 12 12Catalyst performance evaluation results • Desulfurization activity 8.553.33 • Tolerance to the inhibiting effects by H₂S 0.34 0.22 B acidcontent: Brφnsted acid content Tolerance to the inhibiting effects byH₂S: Relative desulfurization activity (a)/(b) in percentage, where (a)is the activity with Sample Oil 5 tested under the conditions II and (b)is the activity with Sample Oil I tested under the conditions I.

As shown in FIG. 1, Catalyst A₂ has a much higher activity thanComparative Catalyst A, even with the DMDS-added sample oil, i.e., thesample oil which produces a larger quantity of hydrogen sulfide, bywhich is meant that Catalyst A₂ has notably improved tolerance to theinhibiting effects by H₂S. It is considered that the improved tolerancemainly results from the interactions of the spill-over hydrogen formingsites (Ni) with the silica-alumina carrier. FIG. 2 shows that thetolerance to the inhibiting effects by H₂S increases linearly with Bacid content of the catalyst. As shown in Table 4, it is also noted thatCatalyst A₀ on the mesoporous silica-alumina carrier has a much higherdesulfurization activity and tolerance to the inhibiting effects by H₂Sthan Catalyst A₃ on the amorphous silica-alumina carrier of the samesilica content, conceivably resulting from the mesoporous silica-aluminacarrier's larger specific surface area which increases B acid contentand allows the active components to be dispersed more finely.

EXAMPLE Y

Catalysts A₄

96.51 g of aluminium tri-sec-butoxide [Al(sec-OC₄H₉)₃] was mixed andreacted with 800 ml of 2-methylpentane-2,4-diol [CH₃CH(OH)CH₂C(CH₃)₂OH],with stirring, at 80° C. for 5 h, to which 69.3 g of tetraethoxysilane[Si(OC₂H₅)₄] was added to be further reacted with the above at 80° C.for 12 h, with stirring, to form a homogeneous solution. Then, 225.8 mlof water was dropped to the above solution at 1 ml/min, for hydrolysisat 80° C. On completing the hydrolysis, the product gel was dried at 90°C. and calcined at 600° C. for 5 h in a flow of air, to prepare thesilica-alumina composition. It contained silica at 50 wt. %.

Next, 7.79 g of nickel nitrate [Ni(NO₃)₂.6H₂O], 9.81 g of ammoniummolybdate [(NH₄)₆Mo₇O₂₄.4H₂O], and 4.33 g of citric acid were dissolvedin 56.2 g of a mixed solution of concentrated ammonia water and purewater, to prepare the solution for impregnation. Composition of themixed solution of ammonia water and water was set to adjust the solutionfor impregnation at pH=9, after it dissolved all of the above solutes.The above silica-alumina composition was coimpregnated with the abovesolution for impregnation by the Pore Filling method, dried at 110° C.for 48 h, formed into a disk shape and calcined at 500° C. for 3 h in aflow of air, to prepare Catalyst A₄.

Silica dispersibility of the carrier for Catalyst A₄ was determined bythe ²⁹Si-NMR method under the following conditions. The results are:

{circle around (1)} NMR peak area ratio I 46.2% {circle around (2)} NMRpeak area ratio II 80.2%

The carrier contained B acid at 105 μmol/g.

The spectral peaks of the carrier obtained by the ²⁹Si-NMR (79.5 MHz)method were processed for waveform deconvolution by the least squareadjustment method using the Gaussian function curve into those at −80ppm, −86 ppm, −92 ppm, −98 ppm, −104 ppm and −110 ppm. The above resultsof the NMR analysis were obtained by calculating a peak area ratio,where

{circle around (1)} NMR peak area ratio I is the combined area of thepeaks at −80 ppm, −86 ppm and −92 ppm relative to the total area of allpeaks, and

{circle around (2)} NMR peak area ratio II is the combined area of thepeaks at −80 ppm, −86 ppm, −92 ppm and −98 ppm relative to the totalarea of all peaks.

Catalysts A₅

The silica-alumina carrier for Catalyst A₅ was prepared in the samemanner as that for the carrier for Catalyst A₄, except that aluminiumtriisopropoxide [Al(i-OC₃H₇)₃] was used as the aluminium alkoxide and asilica content of the carrier was adjusted at 40 wt. %. It was thenincorporated with the nickel and molybdenum components, to produceCatalyst A₅. The carrier had NMR peak area ratio I of 71.3% and NMR peakarea ratio II of 93.2%, and contained B acid at 100 μmol/g.

Catalysts A₆

The silica-alumina carrier for Catalyst A₆ was prepared in the samemanner as that for the carrier for Catalyst A₄, except that thecomposition of aluminium triisopropoxide and tetraethoxysilane wasadjusted so as to have a silica content in the silica-alumina of 60 wt.%. It was then incorporated with the nickel and molybdenum components,to produce Catalyst A₆. The carrier had NMR peak area ratio I of 34.4%and NMR peak area ratio II of 72%, and contained B acid at 138 μmol/g.

Catalysts A₇

The silica-alumina carrier for Catalyst A₇ was prepared in the samemanner as that for the carrier for Catalyst A₄, except that thecomposition of aluminium triisopropoxide and tetraethoxysilane wasadjusted to have a silica content in the silica-alumina of 75 wt. %. Itwas then incorporated with the nickel and molybdenum components, toproduce Catalyst A₇. The results are given in Table 6.

Catalysts A₈

The silica-alumina carrier for Catalyst A₈ was prepared in the samemanner as that for the carrier for Catalyst A₄, to have a silica contentof 50 wt. %. It was then incorporated first with the nickel component bythe procedure in which the carrier was immersed in 0.5N ammonia waterfor 2 to 10 days, filtered, washed, dried at room temperature for 24 h,and then the carrier was immersed in a 0.5N aqueous solution of nickelnitrate for 2 to 10 days, filtered, washed, dried at 110° C. for 24 h,and calcined at 500° C. for 3 h in a flow of air. It was thenimpregnated with the molybdenum component by the Pore Filling method,dried, formed into a shape and calcined, to prepare Catalyst A₈.

Comparative Example Y

Comparative Catalyst B

The silica-alumina carrier for Comparative Catalyst B was prepared usingcommercial silica-alumina to have a silica content of 56 wt. %. It wasincorporated with the nickel and molybdenum components in the samemanner as that for Catalyst A₄. The carrier had NMR peak area ratio I of12.8% and NMR peak area ratio II of 32.8%, and contained B acid at 32μmol/g.

Comparative Catalyst C

A commercial silica-alumina carrier containing silica at 60 wt. %. wasincorporated with the nickel and molybdenum components in the samemanner as that for Catalyst A₄, to prepare Comparative Catalyst C. Thecarrier had NMR peak area ratio I of 12% and NMR peak area ratio II of55%, and contained B acid at 48 μmol/g.

Comparative Catalyst D

A commercial silica-alumina carrier containing silica at 40 wt. % wasincorporated with the nickel and molybdenum components in the samemanner as that for Catalyst A₄, to prepare Comparative Catalyst D. Thecarrier had NMR peak area ratio I of 18% and NMR peak area ratio II of30%, and contained B acid at 30 μmol/g.

Properties of Catalysts A₄ to A₈ and Comparative Catalysts B to D aregiven in Table 6.

EXAMPLE Y-1

Sample Oil 4 shown in Table 1 was hydrotreated over Catalysts A₄ to A₈under the hydrotreatment conditions A shown in Table 5, to evaluatetheir catalyst performance with respect to desulfurization activity(HDS 1) and tolerance to the inhibiting effects by H₂S, defined below.The results are given in Table 6.

Comparative Example Y-1

Sample Oil 4 shown in Table 1 was hydrotreated over ComparativeCatalysts B to D under the hydrotreatment conditions A shown in Table 5,to evaluate their catalyst performance with respect to desulfurizationactivity (HDS 1) and tolerance to the inhibiting effects by H₂S. Theresults are given in Table 6.

EXAMPLE Y-2

Sample Oil 6 shown in Table 1 was hydrotreated over Catalysts A₄ to A₈under the hydrotreatment conditions B shown in Table 5, to evaluatetheir relative desulfurization activity (HDS 2), relativedenitrogenation activity (HDN) and relative dearomatization activity(HDA), defined below. The results are given in Table 6.

Comparative Example Y-2

Sample Oil 6 shown in Table 1 was hydrotreated over ComparativeCatalysts B to D under the hydrotreatment conditions B shown in Table 5,to evaluate their relative desulfurization activity (HDS 2), relativedenitrogenation activity (HDN) and relative dearomatization activity(HDA), defined below. The results are given in Table 6.

TABLE 5 Hydrotreatment Conditions A B Reaction temperature (° C.) 310320 Reaction pressure (kg/cm²G) 10 10 Hydrogen gas/sample oil ratio(SCF/B) 2000 800 Liquid hourly space velocity LHSV (h⁻¹) 1.0 1.0

Catalyst Performance Evaluation

HDS 1: Desulfurization activity with Sample Oil 4 for 4,6-DMDBT, treatedunder the hydrotreatment conditions A

Tolerance to the Inhibiting Effects by H₂S

Relative desulfurization activity (a)/(b), where (a) is thedesulfurization activity with Sample Oil 4 for 4,6-DMDBT hydrotreatedunder the conditions A and (b) is the desulfurization activity withSample Oil 1 for 4,6-DMDBT hydrotreated under the conditions A.

HDS 2: Desulfurization activity with Sample Oil 6, treated under thehydrotreatment conditions B, relative to that of Comparative Catalyst C.

HDN: Denitrogenation activity with Sample Oil 6, treated under thehydrotreatment conditions B, relative to that of Comparative Catalyst C.

HDA: Dearomatization activity with Sample Oil 6, treated under thehydrotreatment conditions B, relative to that of Comparative Catalyst C.

²⁹Si-Nuclear Magnetic Resonance Analysis

Analysis Conditions

Nuclear magnetic reson- BRUKER's DSX-400 ance analyzer Analyzed nuclear²⁹Si (79.5 MHz) Analysis mode High-power decoupling/Magic angle spinningExcited pulse flip angle 30 to 45° Latency time 40s or longer Samplerotational speed 7 KHz Window processing Exponential function(coefficient: 50 Hz) Sample pretreatment No pretreatment Peak area Areaof the peak waveform-deconvoluted from the observed spectral patternsStandard sample The peak of 3-(trimethylsilyl) propane sodium sulfonate[(CH₃)₃SiC₃H₆SO₃Na] is regarded to be positioned at 1.46 ppm

Waveform Deconvolution

The observed spectral patterns are deconvoluted by the least squareadjustment method using the Gaussian function curve into 6 peaks. Fullwidth at half maximum of these deconvoluted peaks are given below. Thefull width at half maximum of the peaks at −80.00 ppm and −110.00 ppmare those which make the synthesized spectral patterns from the 6 peaksclosest to the observed spectral patterns. The silica dispersibity isset as follows.

Silica bonds Peak positions (ppm) Full width half max (ppm) Si-4(OAl)−80.00 Calculated Si-3(OAl) −86.00 9.00 Si-2(OAl) −92.00 8.00 Si-1(OAl)−98.00 9.00 Si—O—Si −104.00 9.00 Si—O—Si −110.00 Calculated

TABLE 6 EXAMPLES Y COMPARATIVE EXAMPLES Y Catalyst Catalyst CatalystCatalyst Catalyst Comparative Comparative Comparative A₄, A₅, A₆, A₇,A₈, Catalyst B Catalyst C Catalyst D Carriers SiO₂ content (wt. %) 50 4060 75 50 56 60 40 B acid content (μmol/g) 105 100 138 100 105 32 48 30²⁹Si-NMR analysis results NMR peak area ratio I 46.2 71.3 34.4 16.7 46.212.8 12.0 18.0 NMR peak area ratio II 80.2 93.2 72.0 55.3 80.2 32.8 55.030.0 Active components NiO (wt. %) 4 4 4 4 4 4 4 4 MoO_(a) (wt. %) 16 1616 16 16 16 16 16 CoO (wt. %) — — — — — — — — Catalyst performanceevaluation results HDS 1 16 11 21 16 15 1 4 2.9 Tolerance to the 0.660.52 0.70 0.64 0.80 0.10 0.35 0.25 inhibiting effects by H₂S HDS 2 178145 200 155 178 33 100 78 HDN 158 126 133 122 160 83 100 100 HDA 217 182262 178 183 89 100 95 NMR peak area ratio I: Combined area of the peaksat −80 ppm, −86 ppm and −92 ppm relative to the total area of all peaks.NMR peak area ratio II: Combined area of the peaks at −80 ppm, −86 ppm,−92 ppm and −98 ppm relative to the total area of all peaks.

The results of EXAMPLES and COMPARATIVE EXAMPLES show that the catalystwith the active components of a Group 8 element and Group 6 element hashigh tolerance to the inhibiting effects by H₂S and a high activity,when these active components are supported by the silica-alumina carriercontaining silica at 2 wt. % or more, particularly 30 wt. % or more, andspecified NMR peak ratios I and II to have a sufficient content of Bacid.

EXAMPLES W

Catalysts A₉

The silica-alumina carrier for Catalyst A₉ was prepared in the samemanner as that for Catalyst A₄, except that the silica-aluminacomposition containing 50 wt. % of silica was impregnated with anaqueous solution of magnesium nitrate by the Pore Filling method, whereconcentration of the magnesium nitrate solution was adjusted so as tohave 1 wt. % of MgO in the carrier. It was dried at 110° C. for 48 h,formed into a disk shape, and calcined at 500° C. for 3 h in a flow ofair, to prepare the silica-alumina-magnesia (SiO₂—Al₂O₃—MgO) carrier.

Next, 10.38 g of nickel nitrate [Ni(NO₃)₂.6H₂O], 13.08 g of ammoniummolybdate [(NH₄)₆Mo₇O₂₄.4H₂O], and 5.77 g of citric acid were dissolvedin 54.9 g of a mixed solution of concentrated ammonia water and purewater, to prepare the solution for impregnation. Composition of themixed solution of ammonia water and water was set to adjust the solutionfor impregnation at pH=9, after it dissolved all of the above solutes.The above silica-alumina-magnesia carrier was coimpregnated with theabove solution by the Pore Filling method, dried at 110° C. for 48 h,formed into a disk shape and calcined at 500° C. for 3 h in a flow ofair, to prepare Catalyst A₉. Its composition is given in Table 7.

Catalysts A₁₀

The silica-alumina carrier for Catalyst A₁₀ was prepared in the samemanner as that for the carrier for Catalyst A₉, except that an aqueoussolution of sodium hydroxide was used in place of the magnesium nitratesolution, to have the silica-alumina-sodium oxide (SiO₂—Al₂O₃—Na₂O)carrier containing 1 wt. % of sodium oxide. Then, the same procedure asused for Catalyst A₉ was repeated to prepare Catalyst A₁₀.

The carriers for Catalysts A₉, A₁₀ and A₁₁ were measured for their2,6-DMPy-TPD profiles at 200° C. to 400° C., 400° C. to 600° C. and 600°C. to 800° C. The results are given in Table 7.

Catalysts A₁₁

80.13 g of aluminium triisopropoxide [Al(i-OC₃H₇)₉] was mixed andreacted with 788 ml of 2-methylpentane-2,4-diol [CH₃CH(OH)CH₂C(CH₃)₂OH],with stirring, at 80° C. for 5 h, to which 69.3 g of tetraethoxysilane[Si(OC₂H₅)₄] was added to be further reacted with the above at 80° C.for 12 h, with stirring. Then, 225.8 ml of water was dropped to theabove effluent at 1 ml/min, for hydrolysis at 80° C. On completing thehydrolysis, the product was dried at 90° C., and calcined at 600° C. for5 h in a flow of air, to prepare the silica-alumina compositioncontaining silica at 50 wt. %.

Next, 10.38 g of nickel nitrate [Ni(NO₃)₂.6H₂O], 13.08 g of ammoniummolybdate [(NH₄)₆Mo₇O₂₄.4H₂O], and 5.77 g of citric acid were dissolvedin 54.89 g of a mixed solution of concentrated ammonia water and purewater, to prepare the solution for impregnation. Composition of themixed solution of ammonia water and water was set to adjust the solutionfor impregnation at pH=9, after it dissolved all of the above solutes.The above silica-alumina composition was coimpregnated with the abovesolution by the Pore Filling method, dried at 110° C. for 48 h, formedinto a disk shape, milled into particles of 600 μm to 800 μm indiameter, and calcined at 500° C. for 3 h in a flow of air, to prepareCatalyst A₁₁, which contained MoO₃ and NiO at 20 wt. % and 5 wt. %,respectively, based on the total weight of the catalyst.

EXAMPLE W-1

Sample Oil 6 shown in Table 1 was hydrotreated over Catalysts A₉, A₁₀and A₁₁ under the hydrotreatment conditions B shown in Table 5, toevaluate their desulfurization activity maintenances by measuring theirinitial desufurization activities, and desulfurization activities at 30h and 100 h. The results are given in Table 7.

TABLE 7 EXAMPLES W Catalyst A₉ Catalyst A₁₀ Catalyst A₁₁ Carriers SiO₂(wt. %) 49.5 49.5 50.0 Al₂O₃ (wt. %) 49.5 49.5 50.0 MgO (wt. %) 1.0 — —Na₂O (wt. %) — 1.0 — Active components NiO (wt. %) 5 5 5 MoO₃ (wt. %) 2020 20 B acid contents Total B acid content (μmol/g) 92 95 105 B acidcontent (μmol/g: 57 57 56 200-400° C.) B acid content (μmol/g: 30 32 34400-600° C.) B acid content (μmol/g: 5 6 15 600-800° C.) Performanceevaluation results^(Note 1)) HDS (initial) 150 150 170 HDS (30h) 130 125140 HDS (100h) 120 115 100 Rate of activity 80 77 59 maintenance(%)^(Note 2)) ^(Note 1))Performance evaluation results Relativedesulfurization activity (HDS): Initial desulfurization activities anddesulfurization activities at 30h and 100h with Catalysts A₉ and A₁₀ andinitial desulfurization activities and desulfurization activities at 30hwith Catalysts A₁₁ relative to desulfurization activities at 100h withCatalysts A₁₁ ^(Note 2))Rate of activity maintenance (%):[HDS(100h)/HDS(initial)] × 100

In comparison with the above Examples and the Comparative Examples,Catalyst A₉ and A₁₀, which contained the respective alkali metal andalkaline earth metal components, and B acid at 50 mmol/g or more, hadalmost the same B acid contents in the 2,6-DMPy-TPD profiles at 200 ° C.to 400° C. and 400° C. to 600° C. as Catalyst A₁₁ containing no alkalimetal, but much lower B acid content at 600° C. to 800° C. than CatalystA₁₁, which was accompanied by improved activity maintenance.

EXAMPLES

Catalysts A₁₂

80.13 g of aluminium triisopropoxide [Al(i-OC₃H₇)₃] was mixed andreacted with 788 ml of 2-methylpentane-2,4-diol [CH₃CH(OH)CH₂C(CH₃)₂OH],with stirring, at 80° C. for 5 h, to which 69.3 g of tetraethoxysilane[Si(OC₂H₅)₄] was added to be further reacted with the above at 80° C.for 12 h, with stirring. Then, 225.8 ml of water was dropped to theabove effluent at 1 ml/min, for hydrolysis at 80° C. On completing thehydrolysis, the product was dried at 90° C., and calcined at 600° C. for5 h in a flow of air, to prepare the silica-alumina compositioncontaining silica at 50 wt. %.

The silica-alumina composition was impregnated with an aqueous solutionof boric acid by the Pore Filling method, where concentration of theboric acid solution was adjusted to have 5 wt. % of boria (B₂O₃) in thecarrier. It was dried at 110° C. for 48 h, and calcined at 500° C. for 3h in a flow of air, to prepare the silica-alumina-boria(SiO₂—Al₂O₃—B₂O₃) carrier. Its total B acid content was 135 μmol/g.

Next, 13.77 g of ammonium molybdate [(NH₄)₆Mo₇O₂₄.4H₂O], 10.92 g ofnickel nitrate [Ni(NO₃)₂.6H₂O], and 6.07 g of citric acid were dissolvedin 57.8 g of a mixed solution of concentrated ammonia water and purewater, to prepare the solution for impregnation. Composition of themixed solution of ammonia water and water was set to adjust the solutionfor impregnation at pH=9, after it dissolved all of the above solutes.The above silica-alumina composition was coimpregnated with the abovesolution by the Pore Filling method, dried at 110° C. for 48 h, formedinto a disk shape, milled into particles of 600 μm to 800 μm indiameter, and calcined at 500° C. for 3 h in a flow of air, to prepareCatalyst A₁₂, which contained MoO₃ and NiO at 20 wt. % and 5 wt. %,respectively, based on the weight of the catalyst. Its properties aregiven in Table 8.

Catalysts A₁₃

The silica-alumina carrier for Catalyst A₁₃ was prepared in the samemanner as that for the carrier for Catalyst A₁₂, except that titania(TiO₂) was used in place of boria (B₂O₃), to have thesilica-alumina-titania (SiO₂—Al₂O₃—TiO₂) carrier. Then, the carrier wasincorporated with the MoO₃ and NiO as the active components to prepareCatalyst A₁₃. Its properties are given in Table 8.

Catalysts A₁₄

The silica-alumina carrier for Catalyst A₁₄ was prepared in the samemanner as that for the carrier for Catalyst A₁₂, except that zirconia(ZrO₂) was used in place of boria (B₂O₃), to have thesilica-alumina-zirconia (SiO₂—Al₂O₃—ZrO₂) carrier. Then, the carrier wasincorporated with the MoO₃ and NiO as the active components to prepareCatalyst A₁₄. Its properties are given in Table 8.

Catalysts A₁₅

The silica-alumina carrier for Catalyst A₁₅ was prepared in the samemanner as that for the carrier for Catalyst A₁₂, except that thoria(ThO₂) was used in place of boria (B₂O₃), to have thesilica-alumina-thoria (SiO₂—Al₂O₃—ThO₂) carrier. Then, the carrier wasincorporated with the MoO₃ and NiO as the active components to prepareCatalyst A₁₅. Its properties are given in Table 8.

EXAMPLES S-1

Sample Oil 4 shown in Table 1 was hydrotreated over Catalysts A₁₂ to A₁₅and Catalyst A₁₁ under the hydrotreatment conditions A shown in Table 5,to evaluate their catalyst performance with respect to desulfurizationactivity (HDS 1) and tolerance to the inhibiting effects by H₂S. Theresults are given in Table 8.

EXAMPLES S-2

Sample Oil 6 shown in Table 1 was hydrotreated over Catalysts A₁₂ to A₁₅and Catalyst A₁₁ under the hydrotreatment conditions B shown in Table 5,to evaluate their catalyst performance with respect to relativedesulfurization activity (HDS 2), relative denitrogenation activity(HDN) and relative dearomatization activity (HDA).

HDS 2, HDN and HDA are the activities relative to those with CatalystA₁₁.

TABLE 8 EXAMPLES S Catalyst A₁₂ Catalyst A₁₃ Catalyst A₁₄ Catalyst A₁₅Catalyst A₁₁ Carriers 5% B₂O₃ 5% TiO₂ 5% ZrO₂ 5% ThO₂ 47.5% SiO₂ 47.5%SiO₂ 47.5% SiO₂ 47.5% SiO₂ 50% SiO₂ 47.5% Al₂O₃ 47.5% Al₂O₃ 47.5% Al₂O₃47.5% Al₂O₃ 50% Al₂O₃ Contents of active components 20% MoO₃—5% NiOTotal B acid content(μmol/g) 135 125 120 112 105 B acid content(μmol/g:200-400° C.) 73 68 65 58 56 B acid content(μmol/g: 400-600° C.) 45 42 4040 34 B acid content(μmol/g: 600-800° C.) 17 15 15 14 15 Performanceevaluation results HDS 1 22 21 20 19 16 Tolerance to the inhibitingeffects by H₂S 0.75 0.70 0.71 0.68 0.66 HDS 2 130 125 110 105 100 HDN120 105 105 103 100 HDA 125 107 110 105 100 Notes) HDS 1:Desulfurization activity with Sample Oil 4 under the hydrotreatmentconditions A HDS 2: Relative desulfurization activity, i.e.desulfurization activity with Sample Oil 6 over a catalyst under thehydrotreatment conditions B, relative to that over Catalyst A₁₁.Tolerance to the inhibiting effects by H₂S: (Desulfurization activitywith Sample Oil 4 under the hydrotreatment conditions A)/(Desulfurization activity with Sample Oil 1 under the hydrotreatmentconditions A) HDN: Relative denitrogenation activity, i.e.,denitrogenation activity with Sample Oil 6 over a catalyst under thehydrotreatment conditions B, relative to that over Catalyst A₁₁. HDA:Relative dearomatization activity, i.e., dearomatization activity withSample Oil 6 over a catalyst under the hydrotreatment conditions B,relative to that over Catalyst A₁₁.

EXAMPLES above show that the catalysts with the metallic component ofboria or the like as the third component contained a B acid content of50 μmol/g or more with notably increased medium weak B acid contents,and exhibited improved tolerance to the inhibiting effects by H₂S, ahigh desulfurization activity for difficult-to-remove sulfur compounds,and also high denitrogenation and dearomatization activities.

EXAMPLE Z

Catalyst A₁₆

The silica-alumina carrier for Catalyst A₁₆ was prepared in the samemanner as that for Catalyst A₁₂, to contain 50 wt. % of silica. Next,12.07 g of phosphomolybdenic acid (H₃(PMo₁₂O₄₀.6H₂O), 10.50 g of nickelnitrate [Ni(NO₃)₂.6H₂O], 5.83 g of citric acid were dissolved in 61.6 gof a mixed solution of concentrated ammonia water and pure water, toprepare the solution for impregnation. Composition of the mixed solutionof ammonia water and water was set to adjust the solution forimpregnation at pH=9, after it dissolved all of the above solutes. Theabove silica-alumina carrier was coimpregnated with the above solutionby the Pore Filling method, dried at 110° C. for 48 h, formed into adisk shape and calcined at 500° C. for 3 h in a flow of air, to prepareCatalyst A₁₆. Its composition is given in Table 9.

EXAMPLE Z-1

Sample Oils 7 and 6 shown in Table 1 were hydrotreated over CatalystsA₁₆, obtained by EXAMPLE Z, and Catalyst A₁₁ under each set of thehydrotreatment conditions shown in Table 5, to evaluate theirdesulfurization activities (HDS 1 and HDS 2, described below). Theresults are given in Table 9.

HDS 1: Desulfurization activity with Sample Oil 7 for 4,6-DMDBT underthe hydrotreatment conditions A

HDS 2: Relative desulfurization activity, i.e. desulfurization activitywith Sample Oil 6 over a catalyst under the hydrotreatment conditions B,relative to that over Catalyst A₁₁.

TABLE 9 Catalyst A₁₆ Catalyst A₁₁ Carrier* SiO₂ (wt. %) 50 50 Al₂O₃ (wt.%) 50 50 B acid content (μmol/g) 105 105 Contents of active components**NiO (wt. %) 5 5 MoO₃ (wt. %) 20 20 Content of phosphorus component**P₂O₅ (wt. %) 0.82 — Performance evaluation results HDS 1 8.3 4.8 HDS 2130 100 *SiO₂ and Al₂O₃ contents in the carrier are those based on thewhole carrier, by weight **Contents of the active metallic andphosphorus components are those based on the whole catalyst, by weight

EXAMPLES show that addition of the phosphorus component improvestolerance of the catalyst to the inhibiting effects by nitrogencompounds, thereby greatly enhancing desulfurization activity fordifficult-to-remove sulfur compounds.

Field of Industrial Utilization

The present invention relates to a high-activity hydrotreating catalyst,comprising a carrier containing a specific content of B acid and showinghigh tolerance to the inhibiting effects by hydrogen sulfide, and amethod for hydrotreating hydrocarbon oils using the same, exhibitingnotable effects in hydrotreating hydrocarbon oils containingdifficult-to-remove sulfur compounds, in particular gas oil fractions.Use of the hydrotreating catalyst of the present invention allows deepdesulfurization of sulfur-containing hydrocarbon oils, and greatlycontributes to environmental preservation.

What is claimed is:
 1. A hydrotreating catalyst characterized in that itcomprises a carrier having a Brønsted acid content of 50 μmol/g or more,which supports at least one active component (A) selected from theelements of Group 8 of the Periodic Table, and at least one activecomponent (B) selected from the elements of Group 6 of the PeriodicTable.
 2. The hydrotreating catalyst according to claim 1, wherein saidcarrier comprises at least one material selected from the groupconsisting of silica, alumina, boria, titania, zirconia, hafnia, ceria,thoria, magnesia, calcium oxide, zinc oxide, iron(III)oxide, berylliumoxide, chromium(III)oxide, phosphorus oxides, zeolites and clayminerals.
 3. The hydrotreating catalyst according to claim 1, whereinsaid carrier is a silica-alumina carrier or a silica-alumina-thirdcomponent carrier.
 4. The hydrotreating catalyst according to claim 3,where said third component comprises at least one material selected fromthe group consisting of alkali metal components, alkaline earth metalcomponents, boria, titania, zirconia, hafnia, ceria, thoria, zinc oxide,iron(III)oxide, beryllium oxide, chromium (III) oxide, phosphorusoxides, zeolites and clay minerals.
 5. The hydrotreating catalystaccording to claim 3, wherein said silica-alumina carrier orsilica-alumina-third component carrier has a silica content of at least2 wt. % based on the total weight of the carrier.
 6. The hydrotreatingcatalyst according to claim 3, wherein the content of the thirdcomponent of said silica-alumina-third component carrier is 0.01 wt. %to 50 wt. % as the oxide, based on the total weight of the carrier. 7.The hydrotreating catalyst according to claim 1, wherein the Brønstedacid content of said carrier is 80 μmol/g or more.
 8. The hydrotreatingcatalyst according to claim 1, wherein said active component (A)comprises at least one element selected from the group consisting ofcobalt, nickel, ruthenium, rhodium, palladium, iridium, and platinum,and said active component (B) is molybdenum and/or tungsten.
 9. Thehydrotreating catalyst according to claim 1, wherein said Brønsted acidcontent is 80 μmol/g or more, said active component (A) comprises atleast one element selected from the group consisting of cobalt, nickel,ruthenium, rhodium, palladium, iridium, and platinum, and said activecomponent (B) is molybdenum and/or tungsten.
 10. A hydrotreatingcatalyst comprising a silica-alumina carrier or a silica-alumina-thirdcomponent carrier which supports at least one active component (A)selected from the elements of Group 8 of the Periodic Table and at leastone active component (B) selected from the elements of Group 6 of thePeriodic Table; characterized in that, wherein: (i) the silica contentis at least 30 wt. % based on the total weight of the carrier; (ii) thespectral patterns of the carrier observed by the nuclear magneticresonance analysis [²⁹Si-NMR (79.5 MHz)] are specified by; (1) thecombined area of peaks at −80 ppm, −86 ppm and −92 ppm being at least15% of the total area of all peaks, and (b) the combined area of peaksat −80 ppm, −86 ppm, −92 ppm and −98 ppm being at least 50% of the totalarea of all peaks, and (iii) Brønsted acid content of the carrier is 50μmol/g or more.
 11. The hydrotreating catalyst according to claim 10,wherein the silica content of said silica-alumina carrier or saidsilica-alumina-third component carrier is at least 40 wt. % based on thetotal weight of the carrier.
 12. The hydrotreating catalyst according toclaim 10, wherein said active component (A) comprises at least oneelement selected from the group consisting of cobalt, nickel, ruthenium,rhodium, palladium, iridium, and platinum, and said active component (B)is molybdenum and/or tungsten.
 13. The hydrotreating catalyst accordingto claim 10, where said third component comprises at least one materialselected from the group consisting of alkali metal components, alkalineearth metal components, boria, titania, zirconia, hafnia, ceria, thoria,zinc oxide, iron(III)oxide, beryllium oxide, chromium(III)oxide,phosphorus oxides, zeolites and clay minerals.
 14. The hydrotreatingcatalyst according to claim 10, wherein the content of the thirdcomponent of said silica-alumina-third component carrier is 0.01 wt. %to 50 wt. % as the oxide, based on the total weight of the carrier. 15.A catalyst composition comprising a mixture of hydrotreating catalysts,wherein one of said hydrotreating catalysts is the hydrotreatingcatalyst according to claim 1 and is present in an amount of from about5 wt. % to 50 wt. % based on the total weight of the catalystcomposition.
 16. A method for hydrotreating a hydrocarbon oilcharacterized in that it comprises contacting a hydrocarbon oil withhydrogen under hydrotreating conditions in the presence of ahydrotreating catalyst according to claim
 1. 17. The method forhydrotreating a hydrocarbon oil according to claim 16, wherein saidhydrocarbon oil is a sulfur-containing gas oil fraction.
 18. A catalystcomposition comprising a mixture of hydrotreating catalysts, wherein oneof said hydrotreating catalysts is the hydrotreating catalyst accordingto claim 10 and is present in an amount of from about 5 wt. % to 50 wt.% based on the total weight of the catalyst composition.
 19. A method ofhydrotreating a hydrocarbon oil characterized in that it comprisescontacting a hydrocarbon oil with hydrogen under hydrotreatingconditions in the presence of a hydrotreating catalyst according toclaim
 10. 20. The method for hydrotreating a hydrocarbon oil accordingto claim 19, wherein said hydrocarbon oil is a sulfur-containing gas oilfraction.
 21. The hydrotreating catalyst according to claim 10, whereinBrønsted acid content of the carrier is 80 μmol/g or more.
 22. Thehydrotreating catalyst according to claim 12, wherein Brønsted acidcontent of the carrier is 80 μmol/g or more.